THE EFFECT OF METHYLENE-BLUE PHOTOTREATMENT ON PLASMA-PROTEINS AND IN-VITRO COAGULATION CAPABILITY OF SINGLE-DONOR FRESH-FROZEN PLASMA

Background: Photodynamic virus inactivation of fresh-frozen plasma (FF P) may result In its impaired coagulation capability. Study Design and Methods: Double-volume plasmapheresis samples from 11 donors were div ided in pairs of 250 mL. One group underwent methylene blue (MB) photo treatment (MB-FFP). The other group was treated according to the stand ards of the American Association of Blood Banks for preparation and st orage of FFP. Parameters of hemostasis and clinically important plasma proteins were tested in native plasma, thawed MB-FFP, thawed FFP, and twice-frozen and thawed FFP (FFP-II). Results: Mean activities of fac tor V (73.4 vs. 94.5%; p<0.01), factor VIII (58.1 vs. 86.7%; p<0.001), and fibrinogen (1.8 vs. 2.8 g/L; p<0.001 FFP as compared to those In FFP. The comparison of MB-FP to FFP-II revealed reduced activities of factor VIII (58.1 vs. 85.2%; p<0.001) and fibrinogen (1.8 vs. 2.8 g/L; p<0.001) but no changes in factor V. Activated partial thromboplastin time in MB-FFP was prolonged beyond the upper normal range (+5.3 sec; p<0.001) and prothrombin time increased In MB-FFP versus FFP (+0.96 s ec; p<0.001). Conclusion: MB phototreatment reduces the in vitro coagu lation capacity of FFP, most likely as a result of the effects of an a dditional freezing and thawing procedure and photooxidation-induced pr otein damage.